java - 如何使用集合读取和显示csv文件

Question

我将 tsv 文件的数据添加到列表中。但它反复提供数据。

这是tsv文件

UserID  City    State   Country ZipCode DegreeType  Major   GraduationDate  WorkHistoryCount           TotalYearsExperience CurrentlyEmployed   ManagedOthers   ManagedHowMany
47  Paramount   CA  US  90723   High School     6/1/1999 0:00   3   10  Yes No  0
72  La Mesa CA  US  91941   Master's    Anthropology    1/1/2011 0:00   10  8   Yes No  0
80  Williamstown    NJ  US  8094    High School Not Applicable  6/1/1985 0:00   5   11  Yes Yes 5
98  Astoria NY  US  11105   Master's    Journalism  5/1/2007 0:00   3   3   Yes No  0

这是我的代码

public class tsv_read{

public static void main(String[] arg) throws Exception {

BufferedReader TSVFile = 
    new BufferedReader(new FileReader("tsvfile.tsv"));

String dataRow = TSVFile.readLine();
List<String> list = new ArrayList<String>();
while (dataRow != null){
String[] dataArray = dataRow.split("\t");
for (String item:dataArray) { 

   list.add(item);

    } 
Iterator<String> it = list.iterator();
while (it.hasNext()) {
   String txt = it.next();
   System.out.print(txt);
} 
System.out.println(); // Print the data line.
dataRow = TSVFile.readLine(); 
}

TSVFile.close();

System.out.println();

} //main()
} 

这是我得到的结果

    UserIDCityStateCountryZipCodeDegreeTypeMajorGraduationDateWorkHistoryCountTotalYearsExperienceCurrentlyEmployedManagedOthersManagedHowMany
     UserIDCityStateCountryZipCodeDegreeTypeMajorGraduationDateWorkHistoryCountTotalYearsExperienceCurrentlyEmployedManagedOthersManagedHowMany47ParamountCAUS90723High School6/1/1999 0:00310YesNo0
  UserIDCityStateCountryZipCodeDegreeTypeMajorGraduationDateWorkHistoryCountTotalYearsExperienceCurrentlyEmployedManagedOthersManagedHowMany47ParamountCAUS90723High School6/1/1999 0:00310YesNo072La MesaCAUS91941Master'sAnthropology1/1/2011 0:00108YesNo0
  UserIDCityStateCountryZipCodeDegreeTypeMajorGraduationDateWorkHistoryCountTotalYearsExperienceCurrentlyEmployedManagedOthersManagedHowMany47ParamountCAUS90723High School6/1/1999 0:00310YesNo072La MesaCAUS91941Master'sAnthropology1/1/2011 0:00108YesNo080WilliamstownNJUS8094High SchoolNot Applicable6/1/1985 0:00511YesYes5
  UserIDCityStateCountryZipCodeDegreeTypeMajorGraduationDateWorkHistoryCountTotalYearsExperienceCurrentlyEmployedManagedOthersManagedHowMany47ParamountCAUS90723High School6/1/1999 0:00310YesNo072La MesaCAUS91941Master'sAnthropology1/1/2011 0:00108YesNo080WilliamstownNJUS8094High SchoolNot Applicable6/1/1985 0:00511YesYes598AstoriaNYUS11105Master'sJournalism5/1/2007 0:0033YesNo0

我想要表格格式的输出

Answer 1

你只需要添加

list.clear();

在每次循环运行的开始。

while (dataRow != null){
    list.clear();
    String[] dataArray = dataRow.split("\t");
    // etc.

目前正在发生的事情是您的 List 越来越大...在第一行中，您添加了该行中的所有字段，然后在第二行中添加了所有这些字段到末尾，依此类推...但您永远不会清空列表并重新开始。

另一种解决方案是将 List 声明移动到循环内:

String dataRow = TSVFile.readLine();
while (dataRow != null){
    List<String> list = new ArrayList<String>();
    String[] dataArray = dataRow.split("\t");
    // etc.

这样，您每次都会得到一个新列表。

如果你想知道为什么你正在打印的字段都一起运行，顺便说一下，这是因为你重复调用 System.out.print(txt) 而没有任何类型的分隔器。您可能希望从 System.out.print(txt+"") 开始，直到您决定了您想要的确切格式。